错误C4996：'std :: _ Copy_impl'：使用可能不安全的参数的函数调用 [英] error C4996: 'std::_Copy_impl': Function call with parameters that may be unsafe
问题描述
我知道这个问题在SO中被问过很多次，但这与其他问题有所不同。
xutility（2227）：warning C4996：'std :: _ Copy_impl'
失败代码段
DWORD dwNumberOfNames = pExportDirectory-> NumberOfNames;
LPDWORD dwNames =（LPDWORD）（（LPBYTE）hDLL + pExportDirectory-> AddressOfNames）;
std :: vector< std :: string>出口;
std :: copy（
dwNames，
dwNames + dwNumberOfNames，
[& export，&hDLL]（DWORD dwFuncOffset）
{
std :: string fname = std :: string（（PCHAR）（（PBYTE）hDLL + dwFuncOffset））;
exports.push_back（fname）;
}
）;
编译器错误
错误1错误C4996：'std :: _ Copy_impl'：使用参数
的函数调用可能不安全 - 此调用依赖调用者检查
是否通过值是正确的。要禁用此警告，请使用
-D_SCL_SECURE_NO_WARNINGS。查看关于如何使用Visual C ++的Checked IteratorsC：\Program Files（x86）\ Microsoft Visual Studio
11.0 \VC\include\xutility 2176的文档。
问题
考虑到C4996 ，表示函数已标记为已弃用
问题在哪里？
- 是否使用std :: copy，MS认为是不安全的，将被弃用？
- 是因为我使用了
std :: copy与C数组？ - 是因为我的方式我使用Lambda表达式？
- 如果不推荐使用std :: copy，那么如果我需要可移植的话，可以使用其他方法。
注意
我知道，如何抑制警告，但我很好奇，问题的原因？
此外，同样重要的是我知道，便携式的方式来处理这个问题，而不影响代码质量。
<你不是根据msdn调用
std :: copy ：http://msdn.microsoft.com/en-us/library/x9f6s1wf.aspx 这个函数签名是这样的：
template< class InputIterator，OutputIterator&
OutputIterator copy（
InputIterator _First，
InputIterator _Last，
OutputIterator _DestBeg
）;
这里没有函子/ lambda的地方。
您未调用 std :: copy_if ： http://msdn.microsoft.com/en-us/library/ee384415.aspx
template< class InputIterator，OutputIterator，class BinaryPredicate>
OutputIterator copy_if（
InputIterator _First，
InputIterator _Last，
OutputIterator _Dest，
Predicate _Pred
）;
由于没有输出迭代器，您的谓词也不返回bool。
看起来你想要 std :: transform ：http://msdn.microsoft.com/en-us/library/391xya49.aspx
template< class InputIterator，class OutputIterator，class UnaryFunction>
OutputIterator transform（
InputIterator _First1，
InputIterator _Last1，
OutputIterator _Result，
UnaryFunction _Func
）;
您应该在输出迭代器中返回所需的值。所以它会是这样的：
std :: transform（
dwNames，
dwNames + dwNumberOfNames，
std :: back_inserter（exports），
[& hDLL]（DWORD dwFuncOffset）//这个lambda是WRONG
{
//这行是错误
std :: string fname = std :: string（（PCHAR）（（PBYTE）hDLL + dwFuncOffset））;
return fname;
}
）;
我的lambda是错误的。你需要输入数组的ELEMENTS（我不确定类型）作为lambda的参数，并返回你想要插入到 exports 中的向量。
您可能也不知道 back_inserter 。它在< iterator> 头中。请参阅： http://msdn.microsoft.com/en-us/library/12awccbs.aspx和此处： http://www.cplusplus.com/reference/iterator/back_inserter/ p>
这可能不是100％的答案，但是，我想你可以到达你想去的地方。
I know this question was asked numerous times in SO, but this is a variation from the rest.
Compiler Error: Function call with parameters that may be unsafe
xutility(2227): warning C4996: 'std::_Copy_impl'
Failing Code Snippet
DWORD dwNumberOfNames = pExportDirectory->NumberOfNames;
LPDWORD dwNames = (LPDWORD)((LPBYTE)hDLL + pExportDirectory->AddressOfNames);
std::vector< std::string > exports;
std::copy(
dwNames,
dwNames + dwNumberOfNames,
[&exports, &hDLL](DWORD dwFuncOffset)
{
std::string fname = std::string((PCHAR)((PBYTE)hDLL + dwFuncOffset));
exports.push_back(fname);
}
);
Compiler Error
Error 1 error C4996: 'std::_Copy_impl': Function call with parameters that may be unsafe - this call relies on the caller to check that the passed values are correct. To disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to use Visual C++ 'Checked Iterators' C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include\xutility 2176
Question
Considering, C4996, means the function was marked to be deprecated Where is the problem?
- Is it the use of std::copy, that MS thinks is unsafe and would be deprecated?
- Is it because I have used
std::copywith aC Array? - Is it because of the way I am using Lambda expression?
- If std::copy is deprecated, what is the alternative, if I need to be portable.
Note
I know, how to suppress the warning, but I am curious to know, the root cause of the problem?
Also, equally important for me to know, the portable way to handle this issue without compromising code quality.
You aren't calling std::copy according to msdn: http://msdn.microsoft.com/en-us/library/x9f6s1wf.aspx
That function signature is this:
template<class InputIterator, class OutputIterator>
OutputIterator copy(
InputIterator _First,
InputIterator _Last,
OutputIterator _DestBeg
);
There's no place for a functor/lambda there.
You're not calling std::copy_if either: http://msdn.microsoft.com/en-us/library/ee384415.aspx
template<class InputIterator, class OutputIterator, class BinaryPredicate>
OutputIterator copy_if(
InputIterator _First,
InputIterator _Last,
OutputIterator _Dest,
Predicate _Pred
);
As you have no output iterator, nor does your predicate return a bool.
It looks like you want std::transform: http://msdn.microsoft.com/en-us/library/391xya49.aspx
template<class InputIterator, class OutputIterator, class UnaryFunction>
OutputIterator transform(
InputIterator _First1,
InputIterator _Last1,
OutputIterator _Result,
UnaryFunction _Func
);
And you should be returning the value you want in the output iterator. So it'll be something like this:
std::transform(
dwNames,
dwNames + dwNumberOfNames,
std::back_inserter(exports),
[&hDLL](DWORD dwFuncOffset) // This lambda is WRONG
{
// THIS LINE IS WRONG
std::string fname = std::string((PCHAR)((PBYTE)hDLL + dwFuncOffset));
return fname;
}
);
My lambda is wrong. You need the input of the ELEMENTS of your array (I'm not sure of the type) as the argument to the lambda, and return what you want inserted into the exports vector.
You probably also didn't know about back_inserter. It's in the <iterator> header. See here: http://msdn.microsoft.com/en-us/library/12awccbs.aspx and here: http://www.cplusplus.com/reference/iterator/back_inserter/
That may not be 100% of the answer, but with that, I think you can get to where you want to go.
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